Process for enhancing electrostatic separation in the beneficiation of ores

ABSTRACT

An electrostatic modification reagent as described herein. The electrostatic modification reagent may be used in an electric separation process for separating components from a mineral ore or sand.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority to U.S. ProvisionalApplication No. 61/110,282, filed Oct. 31, 2008 and U.S. ProvisionalApplication No. 61/171,305, filed Apr. 21, 2009 the contents of whichare incorporated herein by reference in their entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to the field of separating certain mineralcomponents of an ore from other mineral components of the same ore usingelectrostatic separation. Specifically, the present invention relates toelectrostatic modification reagents and methods of using them in anelectrostatic separation process to separate the mineral componentswithin the ore with improved efficiency.

2. Description of the Related Art

Processing and refining many types of mineral ores, including mineralsands, sometimes known as beneficiation, generally involves theseparation of certain mineral components from other mineral components.

For example a single ore or mineral sand may typically include bothrutile and zircon. Both of these mineral have independent uses and mustbe separated from one another. Such a mineral sand may also includeilmenite, monazite, quartz, staurolite and leucoxene, which also must beseparated form the rutile and zircon. Electrostatic separation is widelyused in the heavy mineral ore or sand industries. An electrostaticseparator applies a voltage typically in the range of 21 to 26 kV acrossthe ore resulting in conductive components such as rutile and ilmeniteto migrate to one end of the separator and the non-conductive componentssuch as zircon to migrate to an opposing end of the separator. Thestream of ground ore or mineral sand is split into two streams and eachstream can be further processed to separate out its respectivecomponents using for example magnetic separation. While electrostaticseparation is an effective process, it is not considered to be highlyefficient.

U.S. Pat. No. 4,131,539 to Ojiri, et al. discloses a method for removingsmall amounts of rutile from zircon sand. This patent teaches heattreating the zircon sand in a non-oxidizing atmosphere in order to alterthe surface electrostatic property of the rutile which is said to makerutile more conductive and the heat treated sand is more easilyseparated by electrostatic separation to reduce the titanium dioxidecontent of the sand. While such heating or roasting can be effective, itis energy intensive and alters the surface properties of the mineralcomponents that may not be desirable in the down stream applications.

U.S. Pat. No. 5,502,118 to Macholdt et al. teaches the use of polymericsalts that are suitable as charge control agents and charge improvers inelectrophotographic toners and developers, in triboelectrically orelectrokinetically sprayable powder coatings, in electric materials andfor the electrostatic separation of polymers and salt minerals. Thisdoes not however pertain to the enhanced separation of mineralcomponents.

In one mineral separation processes, such as that shown in U.S. Pat. No.6,168,029 to Henderson et al., which purports to increase the efficiencyof the process, anionic copolymers of acrylic acid and acrylamidereagents are used. A need thus still exists for an improved, moreefficient reagent and method for separating conductive mineralcomponents from non-conductive mineral components of a common ore ormineral sand. Such improved separation could be applicable not only tothe mining of rutile and zircon, but to any other ore that includes bothnon-conductive and conductive components having a commercial value

SUMMARY OF THE INVENTION

The present invention addresses the aforementioned and other needs byproviding in one embodiment a process for the beneficiation of a mineralsubstrate by electrostatic separation of a dry mixture comprising aconducting component and a non-conducting component, comprising:

intermixing a mineral substrate and an electrostatic modifier to form amixture wherein at least one of said conducting component and saidnon-conducting component is electrostatically modified; and

applying an electric field to the mixture to thereby at least partiallyseparate the electrostatically modified component from the mixture;

wherein the electrostatic modifier comprises a

an organic compound selected from the group consisting of quaternaryamines; imidazoline compounds; dithiocarbamate compounds; pyridinecompounds; pyrrolidine compounds; conducting polymers,polyethyleneimines; compounds of the formula (IV):R—(CONH—O—X)_(n)  (IV)

wherein n in formula (IV) is 1 to 3; wherein R in formula (IV) comprisesfrom 1 to 50 carbons; and wherein each X in formula (IV) is individuallyselected from the group consisting of H, M and NR′₄, where M is a metalion and each R′ is individually selected from the group consisting of H,C₁-C₁₀ alkyl, C₆-C₁₀ aryl, C₇-C₁₀ aralkyl and C₁₀-C₁₈ naphthylalkyl;

compounds of formula (VI):

wherein R₈ in formula (VI) is selected from H, C₁-C₂₂ alkyl, C₆-C₂₂aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl, X in formula (VI) isselected from the group consisting of H, M and NR′₄, where M is a metalion and each R′ is individually selected from the group consisting of H,C₁-C₁₀ alkyl, C₆-C₁₀ aryl, C₇-C₁₀ aralkyl and C₁₀-C₁₈ naphthylalkyl;

and mixtures thereof.

The present invention further relates to a process for the beneficiationof a mineral substrate by electrostatic separation of a dry mixturecomprising a conducting component and a non-conducting component,comprising the steps of:

intermixing a mineral substrate and an electrostatic modificationreagent to form a mixture wherein at least one of said conductingcomponent and said non-conducting component is electrostaticallymodified; and

applying an electric field to the mixture to thereby at least partiallyseparate the electrostatically modified component from the mixture;

wherein the electrostatic modification reagent comprises at least oneelectrostatic modifier and a plurality of particles having an averagespecific resistivity that is greater than or equal to the specificresistivity of the non-conducting component when the non-conductingcomponent is electrostatically modified and/or a plurality of particleshaving an average specific resistivity that is less than or equal to thespecific resistivity of the conducting component when the conductingcomponent is electrostatically modified.

In another embodiment, the electrostatic modification reagent comprisesan electrostatic modifier and a plurality of particles, each of saidparticles having a specific resistivity that is greater than or equal tothe specific resistivity of the non-conducting component when thenon-conducting component is electrostatically modified or a plurality ofparticles having a specific resistivity having less than or equal to thespecific resistivity of the conducting component when the conductingcomponent is electrostatically modified.

In another embodiment, the electrostatic modification reagent comprisesan electrostatic modifier, preferably an organic compound, and pluralityof particles, each of said particles having a specific resistivity thatis greater than or equal to the specific resistivity of thenon-conducting component when the non-conducting component iselectrostatically modified and/or a plurality of particles having aspecific resistivity having less than or equal to the specificresistivity of the conducting component when the conducting component iselectrostatically modified. The organic compound can be a polymer or anon-polymer. In another embodiment of the present invention, theelectrostatic modification reagent comprises a polymer and a pluralityof particles, each of said particles having a specific resistivity thatis greater than or equal to the specific resistivity of thenon-conducting component when the non-conducting component iselectrostatically modified and/or a plurality of particles having aspecific resistivity of less than or equal to the specific resistivityof the conducting component when the conducting component iselectrostatically modified.

In another embodiment of the present invention, the electrostaticmodification reagent comprises an organic, polymer or a non-polymer,compound selected from the group consisting of quaternary amines;imidazoline compounds; dithiocarbamate compounds; pyridine compounds;pyrrolidine compounds; conducting polymers such as polypyrroles,polythiophenes and polyanilines; polyethyleneimines; compounds of theformula (IV):R—(CONH—O—X)_(n)  (IV)

wherein n in formula (IV) is 1 to 3; wherein R in formula (IV) comprisesfrom 1 to 50 carbons; and wherein each X in formula (IV) is individuallyselected from the group consisting of H, M and NR′₄, where M is a metalion and each R′ is individually selected from the group consisting of H,C₁-C₁₀ alkyl, C₆-C₁₀ aryl, C₇-C₁₀ aralkyl and C₁₀-C₁₈ naphthylalkyl;

compounds of formula (VI):

wherein R₈ in formula (VI) is selected from H, C₁-C₂₂ alkyl, C₆-C₂₂aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl, X in formula (VI) isselected from the group consisting of H, M and NR′₄, where M is a metalion and each R′ is individually selected from the group consisting of H,C₁-C₁₀ alkyl, C₆-C₁₀ aryl, C₇-C₁₀ aralkyl and C₁₀-C₁₈ naphthylalkyl; andmixtures thereof and a plurality of particles having a specificresistivity that is greater than or equal to the specific resistivity ofthe non-conducting component when the non-conducting component iselectrostatically modified and/or a plurality of particles having aspecific resistivity of less than or equal to the specific resistivityof the conducting component when the conducting component iselectrostatically modified.

The present invention provides a means for improving the efficiency ofelectrostatic separation of conductive minerals from non-conductiveminerals. A specific advantage of the present invention is to provideimproved zircon and rutile product quality. Another advantage of thepresent invention is that it increases zircon and rutile productionrates as opposed to conventional methods. Yet another advantage of thepresent invention is that it reduces the loss of zircon or rutile duringprocessing. Still yet another advantage of the present invention is thatit reduces the middlings and the recycling load of zircon or rutileduring processing.

These and other embodiments, objects and advantages are described ingreater detail below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Electrostatic separation is a method of separation based on thedifferential attraction or repulsion of charged particles under theinfluence of a sufficiently strong electric field. Electrostaticseparation is widely used in various industries, including the heavymineral sand industries. The beneficiation of many types of mineral ore,including heavy mineral sands, involves the separation of certainvaluable mineral components from other valuable or non-valuable mineralcomponents. Mineral separation plants used in the titanium mineralprocessing industry operate using similar process technologies that areoften custom-designed to individual ore bodies and their separationrequirements. Factors that influence the selection of a particularseparation methodology include geology, mineral grade, particle size andshape, type of mineral, inclusions, surface coatings and the interferingspecies present, and the physical characteristics of the minerals. Forexample, a single ore or mineral sand may include both rutile andzircon. Both of these minerals have independent uses and therefore it isoften desirable to separate relatively pure versions of each from theother, and from other impurities such as ilmenite, monazite, quartz,staurolite and leucoxene.

Electrostatic separation can be used for separating rutile and zirconsince rutile is a conductive material and zircon is a non-conductivematerial. Electrostatic separation may be practiced by employing anelectrostatic separator that applies a voltage in the range of 21-26 kVacross the ore, causing the conductive components such as rutile andilmenite to migrate to one end of the separator and the non-conductivecomponents such as zircon to migrate to an opposing end of theseparator. Thus, the stream of ground ore or mineral sand is split intotwo primary streams by the electrostatic separator to separate theconductive components from the non-conductive components. Electrostaticseparation in accordance with the present invention can be used toseparate a variety of mineral systems. These systems include, but arenot limited to, mineral sand, ilmenite/staurolite, ilmenite/monazite,rutile/zircon, zircon/leucoxene, iron ore/silicate, hard rock ilmenite,hard rock rutile, metal recycling, kyanite/zircon, cromite/garnet, andcelestite/gypsum.

Various embodiments of the present invention provide electrostaticmodification reagents and methods of using them to improve thebeneficiation of mineral substrates by improving the efficiency ofelectrostatic separation. In an embodiment, the electrostaticmodification reagent comprises an organic non polymer compound. Inanother embodiment, the electrostatic modification reagent comprises anorganic polymer or non-polymer compound and a plurality of nonconductiveparticles. In still further embodiments, the electrostatic modificationreagent comprises an organic polymer or non-polymer compound and aplurality of conductive particles. In still further embodiments, theelectrostatic modification reagent comprises at least one organiccompound and a plurality of conductive particles and nonconductiveparticles.

In an embodiment, the electrostatic modification reagent comprises anorganic polymer or non-polymer compound selected from the groupconsisting of quaternary amines; imidazoline compounds; dithiocarbamatecompounds; pyridine compounds; conducting polymers such as polypyrroles,polythiophenes and polyanilines; a polyethyleneimine; a pyrrolidonium; acompound of the formula (IV):R—(CONH—O—X)_(n)  (IV)

wherein n in formula (IV) is 1 to 3; wherein R in formula (IV) comprisesfrom 1 to 50 carbons; and wherein each X in formula (IV) is individuallyselected from the group consisting of H, M and NR′₄, where M is a metalion and each R′ is individually selected from the group consisting of H,C₁-C₁₀ alkyl, C₆-C₁₀ aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl;

a compound of formula (VI):

wherein R8 in formula (VI) is selected from H, C₁-C₂₂ alkyl, C₆-C₂₂aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl; X in formula (VI) isselected from the group consisting of H, M and NR′₄, where M is a metalion and each R′ is individually selected from the group consisting of H,C₁-C₁₀ alkyl, C₆-C₁₀ aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl;and mixtures thereof.

In an embodiment the quaternary amine comprises a compound of theformula (I),R(R₁R₂R₃)N⁺X⁻  (I)

wherein R in formula (I) comprises from about 1 to about 50 carbons;wherein R₁, R₂ and R₃ in formula (I) are individually selected from thegroup consisting of H, C₁-C₁₀ alkyl, C₆-C₁₀ aryl, C₇-C₁₀ aralkyl, andC₁₀-C₁₈ naphthylalkyl; and wherein X is selected from halide, oxide,sulfide, nitride, hydride, peroxide, hydroxide, cyanide, perchlorate,chlorate, chlorite, hypochlorite, nitrate, nitrite, sulfate, sulfite,phosphate, carbonate, acetate, oxalate, tosylate, cyanate, thiocyanate,bicarbonate, permanganate, chromate, and dichromate. In an embodimentthe quaternary amine has a number molecular weight of about 700 or less,more preferably, 450 or less.

By imidazoline compounds is meant to designate unsubstituted as well assubstituted imidazolines, quaternized imidazolines and salts thereof. Inan embodiment of the present invention the imidazoline compoundcomprises a compound selected from compounds of the formula (IIa) andtheir quaternized salts and formula (IIb):

wherein R₄′ in formula (IIa) is selected from the group consisting ofC₁-C₄ alkylamine, C₁-C₄ alkoxy and C₂-C₅ alkyl; and wherein R₄ informula (IIa) is selected from the group consisting of H, C₁-C₂₆ alkyl,C₂-C₂₆ alkenyl, C₆-C₂₆ aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl;and wherein R₁ in formula (IIb) is selected from the group consisting ofH, C₁-C₂₆ alkyl, C₂-C₂₆ alkenyl, C₆-C₂₆ aryl, C₇-C₁₀ aralkyl, andC₁₀-C₁₈ naphthylalkyl, oleyl, and wherein R in formula (IIb) is selectedfrom the group consisting of H, C₁-C₂₆ alkyl with and without saturatedor unsaturated, oleyl, C₂-C₂₆ alkenyl, C₆-C₂₆ aryl, C₇-C₁₀ aralkyl, andC₁₀-C₁₈ naphthylalkyl.

By pyrrolidine compounds is meant to designate unsubstituted as well assubstituted pyrrolidine, quaternized pyrrolidine, pyrrolidonium andsalts thereof.

By dithiocarbamate compound is meant to designate compounds comprising adithiocarbamate group as well as salts thereof. In an embodiment of thepresent invention, the dithiocarbamate comprises a diallylaminedithiocarbamate. In another embodiment the diallylamine dithiocarbamateis a sodiumdiallylamine dithiocarbamate of formula VII:

In an embodiment the compound of formula VII has a number molecularweight that is about 450 or less.

By pyridine compound is meant to designate unsubstituted as well assubstituted pyridines and salts thereof, In an embodiment of the presentinvention the pyridine comprises a compound of the formula (III)

wherein R in formula (III) is selected from the group consisting of H,C₁-C₂₂ alkyl, C₆-C₂₂ aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl;and wherein X in formula (III) is selected from halide, oxide, sulfide,nitride, hydride, peroxide, hydroxide, cyanide, perchlorate, chlorate,chlorite, hypochlorite, nitrate, nitrite, sulfate, sulfite, phosphate,carbonate, acetate, oxalate, tosylate, cyanate, thiocyanate,bicarbonate, permanganate, chromate, and dichromate.

In an embodiment of the present invention, the compound of formula IV isselected from monohydroxamic acid, bihydroxamic acid and trihydroxamicacid and any salt thereof. Particularly preferred are C1-C10 alkylhydroxamates, more preferably sodium and potassium alkyl hydroxamates.

In an embodiment of the present invention the conducting polymercomprises a polyaniline, preferably a modified polyaniline comprising arecurring unit of the formula (V):

wherein X, Y, and Z in formula (V) are each individually selected fromthe group consisting of —COOH, —SO₃H, and —CO(NH—OH); wherein R₇ informula (V) is selected from H, C₁-C₂₂ alkyl, C₆-C₂₂ aryl, C₇-C₁₀aralkyl, C₁₀-C₁₈ naphthylalkyl, sulfate, and hydroxyl; and wherein n informula (V) is selected so that the polyaniline has a number molecularweight in the range of about 500 to about 10,000.

In an embodiment of the invention the polyethyleneimine has a molecularweight in the range of about 350 to about 1000 and preferably comprisesa recurring unit of the formula (VIII)

wherein n in formula (VIII) is selected so that the polyethyleneiminehas a molecular weight in the range of about 350 to about 1000; andmixtures thereof.

In an embodiment of the present invention the electrostatic modificationreagent further comprises a plurality of particles having an averagespecific resistivity that is greater than or equal to the specificresistivity of the non-conducting component when the non-conductingcomponent is the component in the mixture to be electrostaticallymodified and/or a plurality of particles having an average specificresistivity that is less than or equal to the specific resistivity ofthe conducting component when the conducting component is the componentof the mixture to be electrostatically modified. The particles in theelectrostatic modification reagent preferably have an average diameterof from 1 to 500 microns.

The weight ratio of electrostatic modifier to particles is preferablyfrom about 100:1 to about 1:100.

Thus, the efficiency of electrostatic separation can be enhanced byincluding a plurality of particles having an average specificresistivity that is greater than or equal to the specific resistivity ofthe non-conducting component, herafter called “non-conductiveparticles”, in the electrostatic modification reagent. In variousembodiments, the electrostatic modification reagent comprises aplurality of non-conductive particles and an organic compound selectedfrom the group consisting of those organic compounds set forth above.The electrostatic modification reagent preferably comprises a pluralityof non-conductive particles and at least one of the organic compoundselected from the group consisting of a quaternary amines; imidazolinecompounds; dithiocarbamate compounds; pyridine compounds; pyrrolidinecompounds; conducting polymers; polyethyleneimines; and mixturesthereof, more preferably at least one compound selected from the groupconsisting of quaternary amines, imidazoline compounds, especiallyquaternized imidazoline compounds, and pyridine compounds. Particularlypreferred are the compounds of formula (I), (IIa), (IIb) and (III).

The plurality of non-conductive particles and the organic compound canbe present in the electrostatic modification reagent in a weight ratioof non-conductive particles:organic compound in the range of about 100:1to 1:100.

In an embodiment, the non-conductive particles are selected from asilicate of the formula (M_(x)O_(y))_(p)(SiO₂)_(q), an aluminate of theformula M_(x)AlO_(z), and mixtures thereof, wherein M is a metal (e.g.,Al, Sn, Zr or Pb); x and y are each individually in the range of about 1to about 4; z is in the range of 1 to about 12; and the ratio p:q is inthe range of from about 10:1 to about 1:10. Other non-conductiveparticles that have a similar size distribution, conductivity andmorphology to the silicate and aluminate particles, can be included inthe electrostatic modification reagent in place of and/or in addition tosuch silicates and aluminates. In another embodiment, the non-conductingparticles are selected from polystyrene, quartz, mica, talc, sulfur,hard rubber, shellac, Lucite, glass powder, dry wood, celluloid, ivoryand mixtures thereof. Further examples of suitable non-conductiveparticles include those that comprise a mineral selected from the groupconsisting of kaolin and montmorillinite. In another example, theplurality of non-conductive particles can comprise aluminosilicate clay.Preferred are non-conductive particles that have a chemical structureand/or composition that is similar to the non-conductive componentpresent in the mineral substrate. When the mineral substrate compriseszircon, the non-conductive particles are preferably selected fromzircon, sand and silica. The non-conductive particles in theelectrostatic modification reagent may be obtained from commercialsources and/or made by techniques known to those skilled in the art.More preferably, the non-conductive particles, especially the silica andzircon particles, have a high purity with iron specification below 1.0%.

The plurality of non-conductive particles in the electrostaticmodification reagent can have an average diameter of less than about 500microns, e.g., less than about 300 microns or less than about 200microns. The non-conductive particles preferably have an averagediameter of at least 1 micron, more preferably of at least 10 microns.Particularly preferred are non-conductive particles having a diameter ofabout 50 to 200 microns. In an embodiment, the non-conductive particleshave an aspect ratio in the range of from about 1 to about 100.

Improved separation is often observed as the particle size of thenon-conductive particles in the electrostatic modification reagent isdecreased. For example, it may be desirable in certain applications touse non-conducting microparticles with the smallest practical particlesize. Often, good results may be obtained using non-conductive particleshaving an average diameter of less than about 200 microns, e.g., lessthan about 100 microns. The plurality of non-conductive particles in theelectrostatic modification reagent may have a unimodal or polymodal(e.g., bimodal) particle size distribution.

In any given situation, the size of the non-conductive particles may beselected on the basis of various practical considerations, such as cost,throughput, the mineral substrate to be treated, the desirability ofexcluding selected impurities, and/or the degree of separation desired.Thus, for example, in some applications a relatively low degree ofseparation may be obtained using an electrostatic reagent that comprisesnon-conducting silicate microparticles having an average particle sizein the range of about 1 to about 500 microns. In other situations, e.g.,when a high degree of separation is desired, smaller non-conductingmicroparticles are often preferred. The sizes of non-conductiveparticles may be determined by measuring their surface areas using theBET N2 adsorption method (see U.S. Patent Publication No. 2007/0007179).Those skilled in the art understand the relationship between particlesize and surface area as determined by the BET N2 adsorption method.

In another embodiment, the efficiency of electrostatic separation isenhanced by including a plurality of particles having an averagespecific resistivity that is less than or equal to the specificresistivity of the conducting component, here after designated as“conductive particles”, in the electrostatic modification reagent.Although this invention is not limited by theory of operation, it isbelieved that the organic compound in the electrostatic modificationreagent selectively attaches the conducting particles to the conductingminerals. In various embodiments, the electrostatic modification reagentcomprises a plurality of conductive particles and an organic polymer ornon-polymer compound, preferably selected from those set forth above.

The electrostatic modification reagent preferably comprises a pluralityof conductive particles and at least one of the organic compoundselected from the group consisting of compounds of formula (IV), (V),(VI), (VII) and (VIII), more preferably a compound of formula (IV).

The plurality of conductive particles and the organic compound can bepresent in the electrostatic modification reagent in a weight ratio ofconductive particles:organic compound in the range of about 100:1 to1:100, e.g., in the range or about 10:1 to about 1:10.

In further embodiments, the conductive particles may comprise a metaloxide of the formula M_(x)O_(y), wherein M is a transition metal, andwherein x and y are each individually in the range of about 1 to about6. The transition metal can be selected from Cu, Co, Mn, Ti, Fe, Zn, Mo,and Ni. In some embodiments, the conductive particles may comprise ametal oxide that is a superconducting material of the formulaA_(p)B_(q)D_(r)O_(s) wherein A is La, Pr, Ce, Nd, Sm, Eu, Gd, Ho, Er,Tm, Yb, Lu, or Nb; B is Ca, Ba, or Sr; D is Cu, Ni, Ti, or Mo, O isoxygen, p is in the range of from about 0.01 to about 2.0; q is in therange of from about 0.5 to about 3; r is in the range of from about 0.1to about 5; and s is in the range of from about 1 to about 10. Thoseskilled in the art will appreciate that in this context the term“superconducting material” refers to a material that is superconductingat a temperature above 4 K, regardless of the temperature of theelectrostatic modification reagent at any given time. Other conductiveparticles that have a similar size distribution, conductivity andmorphology to the metal oxide particles, can be included in theelectrostatic modification reagent in place of and/or in addition tosuch metal oxides.

The plurality of conductive particles can also include any metalparticles such as for example silver, copper, gold, aluminum, iron andmixtures thereof. Other conductive particles can include graphite,covellite, pentlandite, pyrrhotite, galena (lead sulfide), silicon,arsenopyrite, magnetite, chalcocite, chalcopyrite, cassetente pyrite,molybdenite and mixtures thereof. Preferred are conductive particlesthat have a chemical structure and/or composition that is similar to theconductive component present in the mineral substrate. When the mineralsubstrate comprises rutile, the conductive particles are preferablyselected from rutile. More preferably the conductive particles,especially the rutile, have high purity with a presence ofnon-conductive particles such as silica and zircon specification below1.0%.

The plurality of conductive particles can have an average diameter ofless than about 100 microns, e.g., less than about 50 microns. Theconductive particles preferably have an average diameter of at least 1micron, more preferably of at least 10 microns. Particularly preferredare conductive particles having a diameter of about 10 to 100 microns.The sizes of conductive particles may be determined by measuring theirsurface areas using the BET N2 adsorption method (see U.S. PatentPublication No. 2007/0007179). Those skilled in the art understand therelationship between particle size and surface area as determined by theBET N2 adsorption method. The conductive particles in the electrostaticmodification reagent may be obtained from commercial sources and/or madeby techniques known to those skilled in the art.

The electrostatic modification reagent may optionally compriseadditional ingredients. For example, in an embodiment, an electrostaticmodification reagent comprises a liquid such an alcohol and/or water. Inanother embodiment, an electrostatic modification reagent comprises adispersant. In another embodiment, an electrostatic modification reagentcomprises a liquid such as an alcohol and/or water, and a dispersant.The amounts of the electrostatic modification reagent, optional liquidand optional dispersant may vary over a broad range, which may bedetermined by routine experimentation guided by the disclosure providedherein. For example, in an electrostatic modification reagentembodiment, the amount of liquid (e.g., water, oil (e.g., mineral oil,synthetic oil, vegetable oil), and/or alcohol) is in the range of fromzero to about 95%, and the amount of dispersant is in the range of fromzero to about 10%, all of the foregoing amounts being weight percentbased on total weight of the electrostatic modification reagent.

The further inclusion of an optional dispersant in the electrostaticmodification reagent may provide various benefits. For example,inclusion of the dispersant may facilitate dispersal of theelectrostatic modification reagent that contains a liquid, and/or thedispersant may facilitate dispersal of mineral particles and/orimpurities of the mineral substrate with which the electrostaticmodification reagent is intermixed. The dispersant may be an organicdispersant such as a water-soluble polymer or mixture of such polymers,an inorganic dispersant such as a silicate, phosphate or mixturethereof, or a mixture of organic and inorganic dispersants. An exampleof a suitable organic dispersant is a water-soluble or water-dispersiblepolymer that comprises a least one moiety selected from the groupconsisting of carboxyl and sulfonate. Polyacrylic acid andNa-polyacrylate are examples of water-soluble or water-dispersiblepolymers that comprise a carboxyl group.Poly(2-acrylamido-2-methyl-1-propanesulfonate), also known aspoly(AAMPS), is an example of a water-soluble or water-dispersiblepolymer that comprises a sulfonate group. Other suitable organicdispersants include natural and synthetic gums and resins such as guar,hydroxyethylcellulose, and carboxymethylcellulose. The amount ofdispersant is preferably in the range of from zero to about 15 pounds ofdispersant per ton of electrostatic modification reagent.

In another embodiment, the electrostatic modification reagent isprovided in a liquid form, e.g., as a dispersion. For economy, theliquid is preferably water, although the liquid form may comprise otherliquids such as oil and/or alcohol, in addition to or instead of thewater. The liquid is preferably present in an amount that makes theliquid form flowable, e.g., from about 25% to about 95% of liquid byweight based on total weight of the dispersion, more preferably fromabout 35% to about 75%, same basis. Optionally a dispersant may be usedto provide for a uniform and stable dispersion of the components in theliquid. Examples of preferred dispersants include the inorganic andorganic dispersants described above. The amount of dispersant in thedispersion is preferably an amount that is effective to provide a stabledispersion of the insoluble ingredients, e.g., from about 0.1% to about10%, more preferably from about 1% to about 5% by weight based on thetotal weight of the dispersion.

An electrostatic modification reagent may be made in various ways. Forexample, in an embodiment, the electrostatic modification reagent is inthe form of a substantially dry mixture, optionally further comprising adispersant. Such a substantially dry mixture may be formed by, e.g.,intermixing the components, or by suspending, dispersing, slurrying ordissolving the components in a liquid, optionally with heating and/orstifling, then removing the liquid to form a substantially dry mixture.In another embodiment, the electrostatic modification reagent is in theform of a flowable mixture comprising a liquid (e.g., water and/oralcohol), and optionally further comprising a dispersant. As indicatedabove, the electrostatic modification reagent in such a flowable mixturemay be suspended (e.g., colloidal suspension), dispersed (e.g.,dispersion) and/or slurried in the liquid, and/or one or moreheteroatom-containing compounds may be suspended, dispersed, slurriedand/or dissolved in the liquid. Such a flowable mixture may be formed byintermixing the components (in any order), preferably with stirring,optionally with heating. Various formulations may be prepared byemploying routine experimentation informed by the guidance providedherein.

Another embodiment provides a process for the beneficiation of a mineralsubstrate by electrostatic separation of a dry mixture, comprisingintermixing a mineral substrate and an electrostatic modificationreagent to form a mixture comprising an electrostatically modifiedcomponent and applying an electric field to the mixture to thereby atleast partially separate the electrostatically modified component fromthe mixture. The electrostatic modifier present in the modificationreagent selectively associates with one or more components of themineral substrate (e.g., conductive mineral(s) or non-conductivemineral(s)) to thereby form an electrostatically modified component.Upon application of the electric field, separation of theelectrostatically modified component from the remainder of the mixtureis enhanced, relative to separation under substantially similarconditions in the absence of the electrostatic modification reagent. Theelectrostatic modification reagent used in the beneficiation process ispreferably an electrostatic modification reagent as described elsewhereherein.

The mineral substrate is typically provided in a particulate form, e.g.,as a crushed or milled powder. The average particle size of theparticulate mineral substrate is usually less than about 1 mm. In anembodiment, the average particle size of the mineral substrate is lessthan about 500 microns, e.g., less than about 100 microns. In anembodiment, the average particle size of the mineral substrate isgreater than about 10 microns, e.g., greater than about 30 microns. Forexample, in an embodiment, the average particle size of the mineralsubstrate is in the range of about 30 microns to about 100 microns.

The mineral substrate and electrostatic modification reagent can beintermixed in various ways, e.g., in a single stage, in multiple stages,sequentially, reverse order, simultaneously, or in various combinationsthereof. For example, in an embodiment, the various components, e.g.,electrostatic modification reagent, optional ingredients such as water,dispersant, etc. are added to a portion of the mineral substrate to forma pre-mix, then intermixed with the mineral substrate. In anotherembodiment, the electrostatic modification reagent is formed in situ byseparately and sequentially intermixing the components of theelectrostatic modification reagent with the mineral substrate.Alternatively, the electrostatic modification reagent may be addedsimultaneously (without first forming a pre-mix) to the mineralsubstrate. Various modes of addition are effective.

The amount of electrostatic modification reagent intermixed with themineral substrate is preferably an amount that is effective to enhancethe separation of the components of the mineral substrate, e.g., tothereby separate a value mineral from a non-value mineral, anon-conductive mineral form a conductive mineral, upon application of anelectric field. In many cases it is preferable to determine the amountof electrostatic modification reagent to be intermixed with the mineralsubstrate on the basis of the amounts of the individual components inthe electrostatic modification reagent. In an embodiment, theelectrostatic modification reagent is intermixed with the mineralsubstrate at a ratio in the range of about 0.01 kg of electrostaticmodification reagent per ton of mineral substrate to about 5 kg ofelectrostatic modification reagent per ton of mineral substrate. In anembodiment, the electrostatic modification reagent is intermixed withthe mineral substrate at a ratio in the range of about 0.01 kg ofelectrostatic modifier, e.g. organic compound, per ton of mineralsubstrate to about 5 kg of electrostatic modifier, e.g. organiccompound, per ton of mineral substrate. In an embodiment, the pluralityof conducting or non-conducting particles are intermixed with themineral substrate at a ratio in the range of about 0.01 kg of pluralityof particles per ton of mineral substrate to about 5 kg of particles perton of mineral substrate.

At any point prior to the application of the electric field, the pH ofthe mineral substrate may be adjusted, e.g., preferably to a pH in therange of about 6 to about 11, most preferably to a pH in the range ofabout 7 to about 9. To raise pH, one can use any alkali such as sodiumhydroxide, or a blend of sodium silicate and sodium hydroxide.Alternatively, the pH can be adjusted using sodium silicate or soda ash.

Beneficiation or separation of the mixture into mineral components,comprising an electrostatically modified component formed by intermixingthe mineral substrate and the electrostatic modification reagent, may beconducted by applying an electric field to the mixture to therebyseparate the value mineral(s) from the non-value mineral(s). In anembodiment, the mixture is conditioned and dried prior to applying theelectric field. Conditioning times suitable for a particular applicationmay be determined by employing routine experimentation informed by theguidance provided herein. After conditioning, the mixture, comprisingthe electrostatically modified component, is typically dried to form adry mixture having a water content of about 5% or less, e.g., about 2%or less, by weight based on total weight. Suitable drying methods knownto those skilled in the art may be used.

The conditioned and dried mixture containing the electrostaticallymodified component may then be subjected to electrostatic separation.The electrostatic separation is preferably performed at a time that isin the range of from about immediately after conditioning to about 4days after conditioning, e.g., within about 3 days, two days or one dayafter conditioning. Equipment useful for carrying out the electrostaticseparation is commercially available and known to those skilled in theart.

The electrostatic modification reagent is preferably selected to achievea degree of separation between the conductive mineral and thenon-conductive mineral that is greater than the degree of separationobtained in the absence of the electrostatic modification reagent. Morepreferably, the degree of separation is at least about 5% greater, evenmore preferably at least about 10% greater, even more preferably atleast about 15% greater, than a comparable degree of separation achievedin the absence of the electrostatic modification reagent.

After electrostatic separation, the resulting beneficiated product maybe subjected to additional processing steps in order to provide theseparated value mineral(s) and non-value mineral(s) in the form desired.Thus, any desired processing steps, such as for example magneticseparation, may be performed on the resultant beneficiated product,which includes the electrostatically modified component that has been atleast partially separated from the mixture.

The present invention further relates to an electrostatic modificationreagent comprising at least one electrostatic modifier and a pluralityof conducting and-or non-conducting particles in a weight ratio ofelectrostatic modifier to particles from about 100:1 to about 1:100. Inan embodiment, the electrostatic modifier can be a mixture of any andall quaternary amines and/or an imidazoline and pyrrolidonium compoundswith molecular weight ranging from 450-700 and the plurality ofmicroparticles are of any combination of silica or metal silicates orzirconium silicate with size less than 500 micrometer and aspect ratioin the range of 1 to 50 by any ratio by weight.

In an embodiment, the electrostatic modification reagent is added to aheavy mineral concentrate (HMC). In an embodiment, the reagent is addedto a heavy mineral concentrate of size below 700 micrometer (0.7 mmesd).

Some embodiments of process variants for making an improvement in theseparation efficacy of rutile-zircon separation using the process andelectrostatic separation materials of the present invention include, butare not limited to the following (in all the order of addition of thereagent can be reversed, the step of drying can be carried out in anoven or other heating apparatus at a temperature in the range of fromabout 100° to about 180°, electrostatic separation can take place at anytemperature, e.g. from room temperature to about 140° C., including, butnot limited to temperatures as low as 50° C. or lower, and appliedvoltage in the electrostatic separator is from about 21 to about 27 Kv,roll speed is from about 230 to about 300 rolls per minute and feed rateis from about 35 to about 65 kg·hr/in.). Some examples of processvariants for making an improvement in the separation efficacy ofrutile-zircon separation include the following:

1) Make up feed at between 25 to 75% solids in water—add non-conductingsilicate microparticles—then add organic compound of formula (I, IIa,IIb, III or IV)—attrition scrubbing—filter—dry at 140° C.—electrostaticseparation—separate non-conducting and conducting portion—furtherprocessing

2) Make up feed at between 25-75% solids in water—add compound offormula (I or others)—attrition scrubbing—filter—dry at 140°C.—electrostatic separation—separate non-conducting and conductingportion—further processing

3) Make up feed at between 25-75% solids in water—add compound offormula (I or others)—filter—dry at 140° C.—electrostaticseparation—separate non-conducting and conducting portion—furtherprocessing

4) Make up feed at between 25-75% solids in water—add non-conductingsilicate microparticles-then add compound of formula (I or II or III orIV)—filter—dry at 140° C.—electrostatic separation—separatenon-conducting and conducting portion—further processing

5) Make up feed at between 25-75% solids in water—add compound offormula (I or others) in a sump pump—filter—dry at 140° C.—electrostaticseparation—separate non-conducting and conducting portion—furtherprocessing

6) Make up feed at between 25-75% solids in water—add non-conductingsilicate microparticles—then compound of formula (I or II or III or IV)in the sump pump—filter—dry at 140° C.—electrostatic separation—separatenon-conducting and conducting portion—further processing

7) Mix feed at 30-75% solids in water—add compound of formula (I orothers) in the sump pump—centrifuge—dry at 140° C.—electrostaticseparation—separate non-conducting and conducting portion—furtherprocessing

8) Mix feed at 30-75% solids in water—add non-conducting silicatemicroparticles—then compound of formula (I or II or III or IV) in thesump pump—centrifuge—dry at 140° C.—electrostatic separation—separatenon-conducting and conducting portion—further processing

9) Mix feed at 30-75% solids in water—add compound of formula (I orothers) in the sump pump—static mixer—filter—dry at 140°C.—electrostatic separation—separate non-conducting and conductingportion—further processing

10) Mix feed at 30-75% solids in water—add non-conducting silicatemicroparticles—then compound of formula (I or II or III or IV) in thesump pump—static mixer—filter—dry at 140° C.—electrostaticseparation—separate non-conducting and conducting portion—furtherprocessing

11) Add compound of formula (I or others) to the feed at or before wethigh intensity magnetic separator in the process flow—filter—dry at 140°C.—electrostatic separation—separate non-conducting and conductingportion—further processing

12) Make up feed at between 30-75% solids in water—add non-conducting orinsulating silicate microparticles-then compound of formula (I or II orIII) in the sump pump—static mixer—filter—dry at 140° C.—electrostaticseparation—separate non-conducting and conducting portion—Make up feedwith midlings again to 30-75% solids in water—add non-conducting orinsulating silicate microparticles-then compound of formula (I or II orIII)—filter—dry at 140° C. or above—electrostatic separation—separatenon-conducting and conducting portion—further processing.

The process invention provides a means for improving efficiencies ofelectrostatic seaparation of conductive minerals from non-conductiveminerals. Yet another embodiment of the invention is to apply theprocess to mineral mixtures, such as to mineral sand;ilmenite/staurolite mixtures; ilmenite/monazite; rutile/zircon;zircon/leucoxene; hard rock ilmenite/rutile; kyanite/zircon;cromite/garnet; celestite/gypsum; as well as to metal recycling andsilicate removal from iron ore.

When applied to the processing of rutile and zircon containing minerals,the process according to the present invention provides an improvedzircon and rutile product quality, as well as an increased productionrate in comparison with conventional methods. Another advantage of thepresent invention is that it reduces the loss of zircon and/or rutileduring processing. Yet another advantage is that it reduces themiddlings and the recycling load of zircon and/or rutile duringprocessing.

In foregoing embodiments of process variants, further processing mayinclude any one or more of the following: no treatment and electrostaticseparation or reagent treatment, drying and further separation byelectrostatic separation.

Examples 1-7

A bulk quantity of a primarily rutile/zircon mineral substrate feed(25-30 Kg) is passed through a riffle splitter to obtain a number ofmineral substrate sample batches, each containing about 500 g of themineral substrate. The mineral substrate contains about 22% TiO₂ andabout 59-60% ZrSiO₄. Each of the 500 g sample batches are separatelypacked and stored. For each example, a slurry is prepared by intermixingabout 500 g of the dry feed and about 166.0 g of water to result in 75%solids slurry. Amounts of the electrostatic modification reagent shownin Table 1, 0.25 g or 0.5 g (0.5 or 1.0 Kg/T) are intermixed with aportion of the slurry and conditioned with high speed stifling for aboutone minute to form a pre-mix. The remaining slurry is then added to thismixture and conditioned at natural pH for 2, 5, or 10 minutes to form aconditioned slurry. The conditioned slurry is transferred to a tray andthe solution decanted. The tray is placed in an oven at 140° C. forapproximately 3 hours to form a dry mixture containing anelectrostatically modified component. The dry mixture is screenedthrough a screener (size 14) to break any agglomerates. The traycontaining the screened dry mixture is placed in the oven to regain theset temperature. Then the tray is quickly removed from the oven and thescreened dry mixture is passed through an electrostatic separator (modelHTP(25)111-15 from Outotec, Jacksonville, Fla.) at 260 RPM roll speed,applied voltage of 23 kV, and a feed rate of 50 Kg·hr/in. An 18 tray setup is used to collect the product. Trays 1-9 (C) are designated asconducting portion, 10-12 as middlings-1 portion (M1), 13-15 asmiddlings-2 portion (M2), 16-17 as middlings-3 portion (M3) and 18 (NC)as the non-conducting portion. The weights in the above trays arerecorded. An XRF analysis is then performed on each group (conducting,middlings-1,2,3 and non-conducting portion). The mass recovery (weightof each portion) and grades (XRF analysis) are plotted and efficiencycurves are determined.

The efficiency values were first determined for individual trays. It isevaluated by the following calculations. For example for M1:Rutile Recovery (M1),R _(Ti)(M1)=G _(Ti)(M1)×Wt(M1)/G _(Ti)(feed)×Totalfeed wtZircon Recovery (M1),R _(Zr)(M1)=G _(Zr)(M1)×Wt(M1)/G _(Zr)(feed)×Totalfeed wtCumulative Rutile Recovery (M1),CR _(Ti)(M1)=R _(Ti)(C)+R _(Ti)(M1)Cumulative Zircon Recovery (M1),CR _(Zr)(M1)=R _(Zr)(C)+R _(Zr)(M1)Cumulative Efficiency (M1),CE(M1)=[CR _(Ti)(M1)+(100−CR _(Zr)(M1)]/2

Maximum Efficiency (ME) is highest value between cumulative efficienciesCE (C) . . . CE (M2) . . . CE (NC).

As already mentioned, if the reagent improves the separation then theMaximum efficiency (ME) of the separation with the reagent will behigher than the control (no reagent) and the difference (ΔE) of 3 to 5%is significant in the laboratory operation.

TABLE 1 Efficiency Improvement (ΔE) by specific surfactants ExampleElectrostatic ΔE = ME_(Test) − No. Modification Reagent ME_(control) 1Alkyl Immidazoline 2.0 2 Alkyl immidazoline sold as 1.9 Miramine TO-DT 3Quaternary amine sold as 1.0 Aero 3100C 4 Trialkylphosphine oxide 0.9sold as Cyanex 923 5 Sodium diallylamine 2.4 DiThioCarbamate 6Nonylsulfonate soled as 4.4 Witconic 1298 soft 7 Quaternary amine soldas 1.1 Tego Betaine 810

Examples 8-12

A bulk quantity of the feed (25-30 Kg) is passed through a rifflesplitter to provide a good representative feed sample. With continualsplitting procedure, the sample size is reduced to approximately 500 g.Each of the 500 g representative sample batches are separately packedand stored. Each test contained 500 g of dry feed and about 166.0 g ofwater is added to result in a 75% solids slurry. The slurry is thentransferred to an octagonal shaped tall tubular steel container. This isthen placed under a “Delta” drill press. The reagent, 0.5 Kg/T, is addedto this and homogenized for 1 minute. The feed is then added to thismixture and conditioned at natural pH for 10 minutes. The resultingslurry is transferred to a tray and the solution decanted. The tray isplaced in an oven at 140° C. for approximately 3 hours and the treatedfeed screened through a screener (size 14) to break any agglomerates.The tray with the screened sample is placed in the oven to regain theset temperature. Then the tray is quickly removed from the oven and thesample is passed through an electrostatic separator (modelHTP(25)111-15) at 260 RPM roll speed, applied voltage of 23 kV, and feedrate of 50 Kg·hr/in. An 18 tray set up is used to collect the product.Trays 1-9 (C) were designated as conducting portion, 10-12 asmiddlings-1 portion (M1), 13-15 as middlings-2 portion (M2), 16-17 asmiddlings-3 portion (M3) and 18 (NC) as the non-conducting portion. Theweights in the above trays were recorded. XRF analysis is then performedon each group (conducting, middlings-1,2,3 and non-conducting portion).The mass recovery (weight of each portion) and grades (XRF analysis) areplotted to evaluate the efficiency curves.

Maximum Efficiency (ME) is highest value between cumulative efficienciesCE (C) . . . CE (M2) . . . CE (NC).

As stated hereinabove, if the reagent improves the separation then theMaximum efficiency (ME) of the separation with the reagent will behigher than the control (no reagent) and the difference (ΔE) of 3 to 5%is significant in the laboratory operation.

TABLE 2 Efficiency Improvement (ΔE) by Conducting polymers ΔE =ME_(Test) − Examples Reagent ME_(control) 8 Polypyrrole - SO3H 1.4 9Polyaniline-3COOH 2.3 10 Polyaniline (ES) coated on lignin* 1.7 11PolyEthylenelmine 2.6 12 Low MW copolymer of makec 2.0 acid and styrenesulfonate sold as Cyanamer P80

Examples 13-19

A bulk quantity of the feed (25-30 Kg) is passed through a rifflesplitter to ensure a good representative feed sample. With continualsplitting procedure, the sample size is reduced to approximately 500 g.Each of the 500 g representative sample batches are separately packedand stored. Each test contained 500 g of dry feed and about 166.0 g ofwater is added to result in 75% solids slurry. The slurry is thentransferred to an octagonal shaped tall tubular steel container. This isthen placed under a “Delta” drill press. The reagent, 0.5 Kg/T MiramineOT-DT and 0.5 Kg/T of microparticles are added to this and homogenizedfor 1 minute. The feed is then added to this mixture and conditioned atnatural pH for 10 minutes. The resulting slurry is transferred to a trayand the solution decanted. The tray is placed in an oven at 140° C. forapproximately 3 hours and the treated feed screened through a screener(size 14) to break any agglomerates. The tray with the screened sampleis placed in the oven to regain the set temperature. Then the tray isquickly removed from the oven and the sample is passed through anelectrostatic separator (model HTP(25)111-15) at 260 RPM roll speed,applied voltage of 23 kV and a feed rate of 50 Kg·hr/in. An 18 tray setup is used to collect the product. Trays 1-9 (C) are designated asconducting portion, 10-12 as middlings-1 portion (M1), 13-15 asmiddlings-2 portion (M2), 16-17 as middlings-3 portion (M3) and 18 (NC)as the non-conducting portion. The weights in the above trays arerecorded. XRF analysis is then performed on each group (conducting,middlings-1,2,3 and non-conducting portion). The mass recovery (weightof each portion) and grades (XRF analysis) were plotted to evaluate theefficiency curves.

Maximum Efficiency (ME) is highest value between cumulative efficienciesCE (C) . . . CE (M2) . . . CE (NC).

As mentioned before, if the reagent improves the separation then theMaximum efficiency (ME) of the separation with the reagent will behigher than the control (no reagent) and the difference (ΔE) of 3 to 5%is significant in the laboratory operation.

TABLE 3 Efficiency Improvement (ΔE) by the selective attachment ofinsulating particles ΔE = ME_(Test) − Examples Reagent ME_(control) 13Miramine TO-DT(imidazoline) + 1.2 Nanosilica (10 nm) 14 Miramine TO-DT(imidazoline) + 6.0 Silica Fumed 15 Miramine TO-DT (imidazoline) + 6.8Zircon ground 16 Miramine TO-DT (imidazoline) + 5.3 Sand 17 Valine - O(alkyl imidazoline) + 9.8 zircon 18 CP 5596-93 (quaternarized alkyl 8.8imidazoline) + sand 19 Valine - O (alkyl imidazoline) + sand 11.1

Examples 20-23

A bulk quantity of the feed (25-30 Kg) is passed through a rifflesplitter to ensure a good representative feed sample. With continualsplitting procedure, the sample size is reduced to approximately 500 g.Each of the 500 g representative sample batches are separately packedand stored. Each test contained 500 g of dry feed and about 166.0 g ofwater is added to result in 75% solids slurry. The slurry is thentransferred to an octagonal shaped tall tubular steel container. This isthen placed under a “Delta” drill press. The reagent, 0.5 Kg/T alkylhydroxamate (S9849, Cytec Industries) (formula IV) and microparticlesare added to this and homogenized for 1 minute. The feed is then addedto this mixture and conditioned at natural pH for 2, 5 or 10 minutes.The resulting slurry is transferred to a tray and the solution decanted.The tray is placed in an oven 140° C. for approximately 3 hours and thetreated feed screened through a screener (size 14) to break anyagglomerates. The tray with the screened sample is placed in the oven toregain the set temperature. Then the tray is quickly removed from theoven and the sample is passed through an electrostatic separator (modelHTP(25)111-15) at 260 RPM roll speed, applied voltage of 23 kV, and feedrate of 50 Kg·hr/in. An 18 tray set up is used to collect the product.Trays 1-9 (C) are designated as conducting portion, 10-12 as middlings-1portion (M1), 13-15 as middlings-2 portion (M2), 16-17 as middlings-3portion (M3) and 18 (NC) as the non-conducting portion. The weights inthe above trays were recorded. XRF analysis is then performed on eachgroup (conducting, middlings-1,2,3 and non-conducting portion). The massrecovery (weight of each portion) and grades (XRF analysis) are plottedto evaluate the efficiency curves.

Maximum Efficiency (ME) is highest value between cumulative efficienciesCE (C) . . . CE (M2) . . . CE (NC).

As stated hereinabove, if the reagent improves separation then theMaximum Efficiency (ME) of the separation with the reagent will behigher than the control (no reagent). a difference (ΔE) of 3 to 5% issignificant in the laboratory operations.

TABLE 4 Efficiency Improvement (ΔE) by the selective attachment ofConducting Particles ΔE = ME_(Test) − Examples Reagent ME_(control) 20Alkyl Hydroxamate sold as 0.2 S9849 + TiO2 nanoneedles 21 S9849 + TiO2nanoparticles (5 nm) 1.6 22 S9849 + TiO2 powder 0.6 23 S9849 + Rutileground 5.4

What is claimed is:
 1. A process for beneficiating a mineral substrate by electrostatic separation, said mineral substrate comprising a conducting mineral component and/or a non-conducting mineral component, the process comprising the steps of: intermixing the mineral substrate and an electrostatic modification reagent in a liquid medium to form a slurry, wherein at least one of said conducting mineral component and/or said non-conducting mineral component is electrostatically modified; drying said slurry to form a substantially dry mixture; and applying an electric field to the substantially dry mixture, thereby separating at least a portion of the electrostatically modified mineral component from the substantially dry mixture; wherein the electrostatic modification reagent comprises an electrostatic modifier chosen from an organic compound selected from the group consisting of quaternary amines; imidazoline compounds; dithiocarbamate compounds; pyridine compounds; pyrrolidine compounds; conducting polymers; polyethyleneimines; compounds of the formula (IV): R—(CONH—O—X)_(n)  (IV) wherein n is 1 to 3; wherein R of formula (IV) comprises from 1 to 50 carbon atoms; and wherein each X of formula (IV) is individually chosen from a member selected from the group consisting of H, M, and NR′₄, where M is a metal ion and each R′ is individually chosen from a member selected from the group consisting of H, C₁-C₁₀ alkyl, C₆-C₁₀ aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl; compounds of formula (VI):

wherein R₈ is chosen from a member selected from the group consisting of H, C₁-C₂₂ alkyl, C₆-C₂₂ aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl; and X of formula (VI) is chosen from a member selected from the group consisting of H, M, and NR′₄, where M is a metal ion and each R′ is individually chosen from a member selected from the group consisting of H, C₁-C₁₀ alkyl, C₆-C₁₀ aryl, C₇-C₁₀ aralkyl and C₁₀-C₁₈ naphthylalkyl; and mixtures thereof.
 2. The process according to claim 1, wherein the electrostatic modifier comprises a quaternary amine compound according to formula (I): R(R₁R₂R₃)N⁺X⁻X  (I) wherein R of formula (I) comprises from 1 to 50 carbon atoms; wherein each of R₁, R₂ and R₃ are individually chosen from a member selected from the group consisting of H, C₁-C₁₀ alkyl, C₆-C₁₀ aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl; and wherein X of formula (I) is chosen from a member selected from the group consisting of halide, oxide, sulfide, nitride, hydride, peroxide, hydroxide, cyanide, perchlorate, chlorate, chlorite, hypochlorite, nitrate, nitrite, sulfate, sulfite, phosphate, carbonate, acetate, oxalate, tosylate, cyanate, thiocyanate, bicarbonate, permanganate, chromate, and dichromate.
 3. The process according to claim 2, wherein the quaternary amine compound has a number average molecular weight of 700 or less.
 4. The process according to claim 1, wherein the electrostatic modifier comprises an imidazoline compound chosen from a compound of formula (IIa)

or a quaternized salt thereof; wherein R₄′ is chosen from a member selected from the group consisting of C₁-C₄ alkylamine, C₁-C₄ alkoxy and C₂-C₅ alkyl; and wherein R₄ is chosen from a member selected from the group consisting of H, C₁-C₂₆ alkyl, C₂-C₂₆ alkenyl, C₆-C₂₆ aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl; and/or a compound of formula (IIb):

wherein R₁ of formula (IIb) is chosen from a member selected from the group consisting of H, C₁-C₂₆ alkyl, C₂-C₂₆ alkenyl, C₆-C₂₆ aryl, C₇-C₁₀ aralkyl, C₁₀-C₁₈ naphthylalkyl, and oleyl; and wherein R of formula (IIb) is chosen from a member selected from the group consisting of H, C₁-C₂₆ alkyl, oleyl, C₂-C₂₆ alkenyl, C₆-C₂₆ aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl.
 5. The process according to claim 4, wherein the imidazoline compound is chosen from a compound according to formula (IIa), wherein R₄′ is C₁-C₄ alkoxy and R₄ is C₁-C₂₆ alkyl; a compound according to formula (IIb), wherein R is oleyl and R₁ is oleyl; or mixtures thereof.
 6. The process according to claim 5, wherein the compound according to formula (IIa) is:


7. The process according to claim 5, wherein the compound according to formula (IIb) is:


8. The process according to claim 1, wherein the electrostatic modifier comprises a dithiocarbamate compound.
 9. The process according to claim 8, wherein the dithiocarbamate compound is sodiumdiallylamine dithiocarbamate.
 10. The process according to claim 1, wherein the electrostatic modifier comprises a pyridine compound according to formula (III):

wherein R of formula (III) is chosen from a member selected from the group consisting of H, C₁-C₂₂ alkyl, C₆-C₂₂ aryl, C₇-C₁₀ aralkyl, and C₁₀-C₁₈ naphthylalkyl; and wherein X of formula (III) is chosen from a member selected from the group consisting of halide, oxide, sulfide, nitride, hydride, peroxide, hydroxide, cyanide, perchlorate, chlorate, chlorite, hypochlorite, nitrate, nitrite, sulfate, sulfite, phosphate, carbonate, acetate, oxalate, tosylate, cyanate, thiocyanate, bicarbonate, permanganate, chromate, and dichromate.
 11. The process according to claim 1, wherein the electrostatic modifier comprises a conducting polymer comprising a polyaniline compound according to formula (V):

wherein each of X, Y, and Z of formula (V) is individually chosen from a member selected from the group consisting of —COOH, —SO₃H, and —CO(NH—OH); wherein R₇ is chosen from a member selected from the group consisting of H, C₁-C₂₂ alkyl, C₆-C₂₂ aryl, C₇-C₁₀ aralkyl, C₁₀-C₁₈ naphthylalkyl, sulfate, and hydroxyl; and wherein n of formula (V) is selected so that the polyaniline has a number average molecular weight from 500 to 10,000.
 12. The process according to claim 1, wherein the electrostatic modifier comprises a compound of formula (IV) and is chosen from a C₁-C₁₀ alkyl hydroxamate, or salts thereof.
 13. The process according to claim 12, wherein the alkyl hydroxamate is selected from the group consisting of mono-, di-, or tri-hydroxamic acids, sodium salts thereof, potassium salts thereof, and mixtures thereof.
 14. The process according to claim 1, wherein the electrostatic modifier comprises a polyethyleneimine compound according to formula (VIII)

or mixtures thereof wherein n of formula (VIII) is selected so that the polyethyleneimine has a number average molecular weight from 350 to
 1000. 15. The process according to claim 1, wherein the electrostatic modification reagent is intermixed with the mineral substrate in an amount that is from 0.01 kg to 5 kg of electrostatic modifier per ton of mineral substrate.
 16. The process according to claim 1, wherein the mineral substrate comprises rutile and zircon containing minerals. 